Nearly one in 10 children are hospitalized with a primary diagnosis of a mental health condition, and depression alone accounts for $1.33 billion in hospital charges annually, according to a new analysis led by UCSF Benioff Children's Hospital.

The study, which will be published in the April issue of the journal Pediatrics, is the first to examine frequency and costs associated with specific inpatient mental health diagnoses for children, and is a step towards creating meaningful measures of the quality of pediatric hospital care.

"This is the first paper to give a clear picture of the mental health reasons kids are admitted to hospitals nationally," said Naomi Bardach, MD, an assistant professor of pediatrics at UCSF Benioff Children's Hospital and lead author. "Mental health hospitalizations have been increasing in kids, up 80 percent in 2010 compared to 1997. Mental health is a priority topic for national quality measures, which are intended to help improve care for all kids."

More than 14 million children and adolescents in the United States have a diagnosable mental health disorder, yet little is known about which specific mental health diagnoses are causing children to be hospitalized. In the study, researchers found that depression, bipolar disorder and psychosis are the most common and expensive primary diagnoses for pediatric admissions.

"We now know through our analysis of cost and frequency which diagnoses are the most relevant," said Bardach. "Next, we need to define what the optimal care is for children with these conditions so that hospitals can consistently deliver the best care for every child, every time."

Using two national databases - Kids' Inpatient Database and Pediatric Health Information System - the researchers looked at all hospital discharges in 2009 for patients aged three to 20 years old to determine the frequency of hospitalizations for primary mental health diagnoses. They compared the hospitalization rates between free-standing children's hospitals and hospitals that treat both adults and children, to assess if there was a difference in frequency of diagnoses.

The study found that the hospitalization rate for children with primary mental health diagnoses were more than three times higher at general hospitals than free standing children's hospitals, which the researchers say could indicate that general hospitals deliver more inpatient psychiatric care than free-standing children's hospitals.

At both kinds of hospitals, the most common mental health diagnoses were similar (depression, bipolar disorder, and psychosis), which the researchers say supports the creation of diagnosis-specific quality measures for all hospitals that admit children.

Depression accounted for 44.1 percent of all pediatric primary mental health admissions, with charges of $1.33 billion dollars, based on the billing databases used in the study. Bipolar was the second most common diagnosis accounting for 18.1 percent and $702 million, followed by psychosis at 12.1 percent and $540 million.

"These are costly hospitalizations, and being hospitalized is a heavy burden for families and patients. Prevention and wellness is a huge part of the Affordable Care Act, along with controlling costs by delivering great care," said Bardach. "This study helps us understand that mental health is a key priority. The long term goal is not only to improve hospital care for these kids, but also to understand how to effectively optimize mental health resources in the outpatient world."